The aim of this work is to ascertain the very low density human serum lipoprotein apoprotein and subpopulation composition of normal and hyperlipoproteinemic individuals, and to determine the concentration fluctuations as a function of food intake. Lipoproteins will be isolated by preparative ultracentrifugation, apoproteins by chromatographic procedures. Subpopulations will be determined by a new radioimmunoassay. Another aim of this work is to determine the sequence of the carbohydrate units of low density lipoproteins, and to determine the amino acid sequence of the apoprotein moiety of low density lipoproteins. These studies will be carried out using conventional methods. Experiments to study certain aspects of the conversion of very low density lipoprotein to low density and other lipoproteins are planned using various radioactively labeled lipoproteins and apoproteins. The plasma disappearance rate of lipoproteins apoproteins and of lipoprotein subpopulations will be determined.